Fitbit today announced the Fitbit Alta HR, which the company is calling the “world’s slimmest fitness wristband” that has a continuous heart rate monitor. The Alta HR launches just over a year after Fitbit debuted the original Fitbit Alta, which included new “Reminders to Move” to tell users to stand up and move around a bit, like Apple Watch stand notifications.

The main upgrade for the Fitbit Alta HR revolves around its ability to detect the user’s heart rate throughout the day, thanks to the company’s PurePulse technology. Additionally, the Alta HR will include all of the usual Fitbit benefits, like automatic exercise recognition, sleep tracking, a seven day battery life, smart notifications, and more.

Thanks to the bolstered heart rate technology, the Fitbit Alta HR also has a few improved sleep tracking features. “Sleep Stages” can detect how long each user spends in light, deep, and REM sleep, as well as detect how many times the user wakes up. “Sleep Insights” accumulates the large picture of each user’s Fitbit data and actively tries to help “improve your sleep for better overall health.”

Sleep Stages will be available on Alta HR, Blaze and Charge 2 Fitbit devices, while Sleep Insights will be available on any Fitbit “that tracks sleep via the Fitbit app.”

“Alta HR and these powerful new sleep features demonstrate our continued focus on evolving our innovative technology to deliver deeper, more actionable insights to help our users improve their health,” said James Park, co-founder and CEO of Fitbit. “The miniaturization of our PurePulse heart rate technology opens up exciting opportunities for future generations of devices and new form factors. Our advances in sleep will provide millions of users around the globe accessibility to invaluable insights that previously could be obtained only through expensive lab tests.”

The company said that the Fitbit Alta HR is 25 percent slimmer than the Fitbit Charge 2, which is Fitbit’s other heart rate-compatible wearable. The addition of heart rate monitoring will bolster the Alta HR’s ability to better measure calorie burn all day, and subsequently help users stay on track for their fitness goals, according to Fitbit.

Like other Fitbit devices, the Alta HR will also be available in a variety of colors and bands. The basic models come in black, blue gray, fuchsia or coral with a matching aluminum tracker for $149.95. Two special editions include a soft pink classic band with 22k rose gold plated tracker and black classic band with matte gunmetal tracker for $179.95. The Fitbit Alta HR can be pre-ordered today and will launch online and in stores this April.

Although Fitbit remains the leader in the wearable field, the Apple Watch has proven to be a major contender in the market with a strong holiday 2016 boosting consumer knowledge of the Watch, most likely thanks to Apple’s marketing pivot from presenting it as a fashion accessory to a workout/fitness companion. The numbers come from research firm IDC, which simultaneously marked the same quarter as one of Fitbit’s “largest declines ever,” although it still remains atop the market in terms of units shipped and market share.